The present invention relates to occupant position control systems, and more particularly, concerns a method for robust occupant position control prior to vehicle impact.
Automotive manufacturers have incorporated sensing systems and restraint actuators to improve occupant safety. For example, current vehicles typically employ solid-state impact accelerometers to sense decelerations acting upon the vehicle body. In response to the accelerometer outputs, airbags or other safety devices are deployed. Front airbags, side airbags, and seatbelt pretension systems, for instance, play an important role in achieving desired safety performance. In order to achieve optimal functionality, the active restraint systems are required to deploy at appropriate times and must be well coordinated to meet related safety objectives including minimizing head and chest decelerations, upper neck forces and moments, and chest deflections. The seatbelt pretensioner, for example, removes the slack in the seatbelt webbing. This is instrumental in keeping the vehicle occupant in the seat prior to the deployment of airbags or other safety devices.
Current vehicles typically employ solid-state impact accelerometers to sense decelerations acting upon the vehicle body. Sensing algorithms analyze the accelerometer data to evaluate early crash conditions and determine safety device deployment schemes. Integrating the safety restraint systems with accelerometer-based crash sensing systems, improves the overall vehicle safety.
In certain circumstances, however, it would be desirable to provide information from predictive sensors before a vehicle collision such that safety countermeasures can be activated when a collision is inevitable. In this regard, it would be desirable to have reversible seatbelt pretensions to establish the position of an occupant prior to a collision based on information from predictive sensors regarding an imminent crash situation.
It would also be desirable to have an effective, active manipulation of seatbelt pretensioners to achieve improved coordinated injury mitigation with other safety devices such as airbags. It would also be desirable to have an intelligent active pretensioner mechanism, a redundant backup strategy for the pretensioner activation, a reliable pre-crash predictive sensing system, and knowledge of occupant characteristics such as size, weight and position for an improved coordinated injury mitigation scheme. Therefore, there is a need in the art to provide a method for robust occupant position control prior to vehicle impact to accomplish these desires.
The present invention, accordingly, provides a predictive collision sensing system and seatbelt pretensioner control scheme to provide robust occupant position control prior to vehicle impact.
In one aspect of the invention, a method for positioning occupants of a reference vehicle is provided. The method includes, in response to detecting an object, generating a Collision Index (CI) value representing a likelihood of collision with the detected object and the speed dependent severity, and generating a Lateral Displacement (LD) value indicative of a distance to the detected object. A weight value (Wo) for a vehicle occupant is also determined. When the CI and LD values satisfy respective threshold conditions, the method generates a pretensioner output (PTout) value as a function of the CI and Wo values, and activates a seatbelt pretensioner associated with a seat of the vehicle occupant as a function of the PTout value.
In another embodiment a pre-crash occupant positioning system for a vehicle is provided. The system includes an object detector for providing a speed and distance to a detected object, a weight sensor associated with an occupant seat for providing an occupant weight value (Wo), and a seatbelt pretensioner responsive to a pretensioner control signal (PTout) for tensioning a seat belt associated with the occupant seat. A Predictive Impact Estimator (PIE) generates a Collision Index (CI) value as a function of the closing velocity and object distance values. A Pretensioner Control Module (PCM) receives the CI and Wo values, generates a PTout value as a function of the CI and Wo values, and communicates the PTout value to the seatbelt pretensioner.
One advantage of the present invention is that activation of the seatbelt pretensioner system prior to a collision is based on a predicted collision index, and the occupant position can be established before a potential collision occurs. Another advantage of the present invention is that the method for robust occupant position control prior to vehicle impact provides an activation signal to a reversible pretensioner which is dynamically regulated by accounting for occupant characteristics, including weight, to assure the appropriate amount of load is applied to the occupant. Yet another advantage of the present invention is that it provides a signal to a back-up passive pretensioner as to the status of the active pretensioner manipulation. A further advantage of the present inventions is that a confirmation signal is sent to the airbag RCM with the collision index level to assist in multistage air-bag activation based on threshold CI levels, should a collision occur. Yet another advantage of the present invention is that thresholds for activating the pretensioner are tunable based on the collision index value to minimize nuisance manipulation, and to recommend on what safety device to deploy before/after the collision.
Other advantages and features of the invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.